The long term goal of this research is to contribute to the understanding of the sensory control of movement through studies of the cerebral cortex of macaques using physiological and behavioral methods. Emphasis will be placed on the role of primary motor, premotor, and parietal cortex in the control of limb, hand, and head movements. One major aim is to continue current research on the hypothesis that these areas represent movement by means of a stored set of behaviorally useful postures. A second aim is to study how these brain areas adapt as a function of practice with previously atypical movements. A third goal is to continue research on the hypothesis that restricted regions in motor and parietal cortex coordinate movements that defend the body from nearby threatening objects. These experiments will involve electrical stimulation of cortex using low currents (microamps); recording the activity of single neurons in cortex during movement; injection of muscimol, a chemical that temporarily deactivates a small region of cortex; and measuring behavior and muscle activity. This research should contribute to the diagnosis and treatment of disorders of sensory-motor function caused by developmental abnormalities, disease, trauma, aging, and unusual environments such as submersion in water or in outer space. The proposed research may also contribute to the development of limb prosthetics and artificial devices for object manipulation.